-Use wooden baseball bats, which are safer and made from from a renewable resource. Aluminum mining and manufacturing is terribly energy-wasteful and environmentally destructive.
-Use a commercial car wash instead of washing your car at home to save lots of water.
-The manufacture of laptop or notebook computers uses fewer materials and less energy than desktop computers. Using these smaller computers is also more energy efficient.

The lists of earth-friendly ideas goes on and on. Most are actually very easy if you can just remember to do them, such as share a bigger bag of popcorn at the movies instead of buying two bags. A very helpful book.